Various types of hand tools and appliances require control elements having various types of functions. Basic to the control is an ON-OFF switch. Additionally, some tools or appliances desirably should have overload relays, speed control, RF suppression capacitors, reverse rotation switches and the like. The tools for which the present application is particularly adapted are hand tools such as drills, impact or percussion drills, hand circular saws and the like, as well as other appliances. Customary switch elements or combinations of switches usually were so designed that, at the most, two functions were combined in a single switching unit. A typical combination is an ON-OFF switch and an overload protection switch; or an ON-OFF switch combined with a speed control network for electronic control of the operating speed of the motor of the tool or appliance. Adding additional operating functions beyond the two previously used required assembly of an additional circuit element or network unit to the switch. The location of such additional units has resulted in difficulties, particularly since it is desired to reduce the overall size of the machines and especially the handles therefor. Adding functions to the switch unit therefore required differences in the construction of the handle to accomodate the further elements or components. Although the basic tool may be of the same size and construction series, different housings may have to be provided if the basic tool is to have different operating controls. An additional problem arose in that internal connections were necessary within the tool itself to interconnect circuit components and networks if more than two machine functions were to be controlled from any one point. The additional wiring introduced additional labor costs as well as itself requiring additional space for the connecting leads.
Difficulties have been experienced in standardization of components and elements of hand tools, appliances, and the like, if more than two operating functions were to be provided. Additional difficulties arose with placement and location of the required circuit components.
It is an object of the present invention to provide a standard combined, multiple-function switching unit in which various operating functions can be combined so that a single tool or appliance housing can be used and yet different functions of the operating control can be accomodated.